﻿using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;

namespace Infrastructure
{
    /// <summary>
    /// 验证码辅助类
    /// </summary>
    public static class ValidCode
    {
        /// <summary>
        /// 返回一个新的验证码
        /// </summary>
        /// <returns></returns>
        public static string NewValidCode()
        {
            int number;
            char code;
            string checkCode = String.Empty;
            System.Random random = new Random();
            for (int i = 0; i < 4; i++)
            {
                number = random.Next();
                code = (char)('0' + (char)(number % 10));
                checkCode += code.ToString();
            }
            return checkCode;
        }

        /// <summary>
        /// 将验证码生成验证图片
        /// </summary>
        /// <param name="validCode">验证码</param>
        public static Bitmap ValidCodeToImage(string validCode)
        {
            if (validCode == null || validCode.Trim() == String.Empty)
            {
                return null;
            }
            Bitmap image = new Bitmap((int)Math.Ceiling((validCode.Length * 13.5)), 22);
            Graphics g = Graphics.FromImage(image);
            try
            {
                Random random = new Random();
                g.Clear(Color.White);
                for (int i = 0; i < 10; i++)
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);

                    g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                }
                Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
                System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);

                g.DrawString(validCode, font, brush, 2, 2);
                for (int i = 0; i < 10; i++)
                {
                    int x = random.Next(image.Width);
                    int y = random.Next(image.Height);

                    image.SetPixel(x, y, Color.FromArgb(random.Next()));
                }
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                return image;
            }
            finally
            {
                g.Dispose();
            }
        }
    }
}
